Thursday, April 21, 2011

Asdrubal Cabrera and Small Sample Size

It is no secret that Asdrubal Cabrera of the Cleveland Indians is enjoying a nice early season power surge. In just 84 plate appearances he has collected 4 home runs, more than the 3 he hit in the entire 2010 season. In addition, Asdrubal has an ISO of .216, nearly double his career average of .115 and over three times what it was during the 2010 season.

Naturally my first instinct is to try and determine where this sudden power surge came from. However, as you might have already guessed, any analysis on Asdrubal’s numbers to this point would be almost worthless because of Small Sample Size. I capitalized the term because it almost seems like a proper noun at this point. If you gander around the internet right now, you will see it just about everywhere a baseball discussion is occurring. Small Sample Size has become the hip new term this season. Even some ESPN writers have mentioned it instead of immediately praising the would be hero as the next break out star!

All kidding aside, analyzing Asdrubal at this point would seem fruitless, because 84 plate appearances is not enough to get an accurate assessment of any long term pattern changes. However, ignoring our wisdom, when we check the numbers we see that almost nothing has changed for Asdrubal. At this point in the season, Asdrubal has a strikeout rate of 17.6% of at bats and a walk rate of 6% of plate appearance. His career totals are 18% and 8.1% respectively. His BABIP is .293 while his career rate is .330. His batting average and OBP are .281 and .341 as opposed to career rates of .281 and .347. For his batted ball metrics, he has a 16.4% line drive rate per ball in play, a 47.5% ground ball rate per ball in play, and a 36.1% fly ball rate per ball in play. His career batted ball rates are 19.9%, 48% and 32.2% respectively. It should be noted that the 3.9% difference in fly ball rate equate to about 2 fly balls in play at this point in the season, obviously not statistically significant. And to save some time, you will just have to trust me that Asdrubal’s swing percentages are largely the same with no noticeable differences.

In summation, despite a completely insignificant sample, Asdrubal has put up largely identical numbers to his career marks. The only noticeable difference is the dramatic increase in home run per fly ball. So far in 2011 Asdrubal has hit 18.2% of all his fly balls out of the ball park for a home run as compared with a career mark of 5.7%. For comparison sake, Albert Pujols had an 18.3% home run per fly ball rate during the 2010 season.

Now I picked Asdrubal to talk about for a few reasons. First, he has the most noticeable unexpected power surge in the AL Central. Second, I suspected his home run rate would be the only major difference in his numbers as he has been a fairly consistent player over the course of his career. Third, Asdrubal has no noticeable differences in his swing or body or anything else that would make me think he can suddenly hit 26 home runs (roughly 145 fly balls given full time at bats x .182 home runs per fly ball). Cleveland Indians fans feel free to message me if you have noticed anything that would give rise to increased power. It largely appears that at age 25, Asdrubal is still the same player he has been for his major league career.

The temptation now is to say that Asdrubal’s power will regress. That is probably true. However, the way in which the term regress is used can often be misleading.

The natural temptation is to say that because Asdrubal has already hit 4 home runs, and his expected total home runs for a full season of 550 AB would be in the neighborhood of 6-10 (roughly 145 fly balls x .057), that his regression would mean he is likely to only hit 2-6 home runs the rest of the year. However, this would be incorrect.

Regression in this case merely means that he would be expected to match his rates over the long run, but past performance does not dictate future performances. For example, if a roulette wheel lands on black 100 times in a row, the probability that it will land on red on the next spin is still nearly 50% (factoring in the green 0’s). In Asdrubal’s case, just because he hit 4 home runs in a small amount of plate appearances would not mean he is likely to hit home runs at a lower clip than his career rate of 5.7% hr/fb going forward.

As a result, predicting Asdrubal going forward is fairly simple, assuming there has actually not been a long term change in his power, it is simply his career hr/fb rate times the amount of fly balls. In this case it is (550 ab – 74 ab from this season – (.18 so rate x 476)) x .322 fb rate x .057 hr/fb = 7 home runs, possibly 8 if we are generous.

However the implication here is significant, the very fact that Asdrubal started hot by hitting more home runs actually makes it more likely he is going to have an above average season hitting home runs. Regression is not guaranteed to wipe away a hot start. Using his career numbers going forward, his level production nets 11 home runs on the season which of course is 5 more than his career season high of 6.

And of course this does not just go for Asdrubal Cabrera, a hot start, especially with rare events like a home run or triple or even a double, makes it more likely than not that player will finish with an above average season in that department.

1 comment:

ACab has cooled off the last week or so. But, during his HR streak, there were a couple of articles written. According to these articles, the reason for ACab's increase in power was a change in approach at the plate. Apparently, Orlando Cabrera, after watching ACab demonstrate home run power during numerous batting practices, convinced ACab to selectively look for his pitch during at-bats and swing away rather than just make contact, which heretofore has been ACab's approach at the plate. Thus the increase in power. The bottom line, per the articles, is that ACab has more power than he has shown in prior years, he just has chosen not to use it.